I think I was the first to get Collector plates for my 91 back in June 2007 and worked for 18 months to convince Nigel Matthews who was ICBC's collector car manager at the time, to agree to allow stock NSX's in on the limited volume over 15 year old basis.
NSX production volume was split between Honda and Acura reducing NSX production volume and only 698 Canadian market NSX's were made 1991-2005.
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Here is a link to the allowed ICBC Collector car accessories list.
http://www.icbc.com/vehicle-registration/Specialty-vehicles/accessories-parts.pdf
For example you can change the wheels on a stock NSX as long as they are period correct (plus/minus two years from car model year)
As far as I know 17/18 Advan's etc. are not permitted.
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I think the intent of the Collector car program is to offer an insurance discount for special cars that are not driven to work or school (not daily driver's).
When you see a collector plate, the car it's on is supposed to be a well preserved example of a stock unit.
I suppose it add's some provenance and value to a car in that the car has had to pass certain ICBC criteria to get the plate.
As these cars are not racking up high mileages each year and are generally very well cared for the risk/cost to ICBC is reduced and so our insurance premiums are reduced which is a win for all of us.
PM me for details if you like